高三英语教案之表语从句.doc

从句2：表语从句
一、表语从句就是用一个句子作为表语。说明主语是什么或者怎么样，由名词、形容词或相当于名词或形容词的词或短语充当，和连系动词一起构成谓语。
（一）定义
表语从句定义：在一个复合句中，从句作的是主语的表语成分。
（二）表语从句的关系代词
(1) 从属连词that。在从句中不做成分。
如： The trouble is that I have lost his address. 麻烦是我把他的地址丢了。
(2) 从属连词whether, as, as if。
如：He looked just as he had looked ten years before.
他看起来还与十年前一样。
注：从属连词if一般不用来引导表语从句，但as if却可引导表语从句，
如： All this was over twenty years ago, but it’s as if it was only yesterday.
这都是20多年前的事了，但宛如昨天一样。
注：能跟表语从句的谓语动词一般为系动词be, seem, look，sound等。
如： He looked just as he had looked ten years before.
他看起来还与十年前一样。
(3) 连接代词who, whom, whose, what, which, whoever, whatever, whichever 在表语从句中做主语、宾语等。
如：That was what she did this morning
(4) 连接副词 where, when, how, why。
如：What I wonder is when he left. 我想知道他是何时离开的。
(5) 连词because可引导表语从句。
如：I think it is because you are doing too much. 我想这是因为你做得太多。 (6) 在一些表示“建议、劝说、命令”的名词后面的表语从句中，谓语动词用虚拟语气。should+动词原形表示，should可省略。
如： My suggestion is that we (should) start early tomorrow.
我的建议是我们明天一早出发
三、注意
1、表语从句一定要用陈述语序。 　　
False: The question is when can he arrive at the hotel. 　　
Right: The question is when he can arrive at the hotel
2、 不可以用if，而用whether 连接表语从句（as if 例外）。 　　
引导宾语从句时可以互换if/whether，位于介词后要用whether，位于句首时要用whether，引导表语从句，主语从句，同位语从句时要用whethe。r 　　
False: The question is if the enemy is marching towards us. 　　
Right: The question is whether the enemy is marching towards us. 　　
Right: It looked as if he had understood this question.
that在表语从句中不可以省掉。
四、相近辨析
“That is why...”是常用句型， 意为“这就是……的原因/因此……”， 其中why引导的名词性从句在句中作表语， 该句型通常用于针对前面已经说明过的原因进行总结.
例如：I got up very late, that is why I came to school at this moment.
下面是两个与“That is why...”形式相似的结构， 它们与“That is why...”结构之间的关系要能够辨析清楚： 　　
(1）“That is why...”与“That is the reason why...”同义， 只不过从语法结构上讲， “That is the reason why...”中why引导的是—个定语从句， 将其中的the reason去掉则与“That is why...”结构一样.
例如：That is (the reason) why I cannot agree. 这就是我不能同意的理由。 　　
(2）“That is because...”句型中从属连词because引导的名词性从句在此作表语， 这也是个常用句型， 意为“这就是为什么……/因为……”。“That is because...”与“That is why...”之间的不同在于“That is because...”指原因或理由， “That is why...”则指由于各种原因所造成的后果.
例如：He did not see the film last night. That is because he had to help his little sister with her homework.
昨天晚上他没有去看电影， 那是因为他得帮助他的妹妹做作业。
（第一句话说明结果， 第二句话说明原因） 　　
He had seen the film before. That is why he did not see it last night.
他以前曾看过那部电影， 因此他昨天晚上没有去看。
（第一句话说明原因， 第二句话说明结果）

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